Bukkit

What is the enhancement in mind? How should it look and feel?
Make it so that a player can use a command to apply a potion effect to their 'weapon' so that when they interact via left clicking (or even right clicking so as to perhaps not interfere with other plugins as much?) with another player while holding that 'weapon' it could transfer that effect to the player they interacted with.

Please provide any additional information below.
I would recommend that you implement the following options as well:

1. My request only concerns PvP.  I personally have no desire for effects to be applied to PvE creatures.  However the PvE question will cross your mind and perhaps others would be interested in PvE targets being affected.

2. Prevent stackability of effects.  A player can only apply one effect to their weapon.  I could see this being a programming nightmare to implement some kind of control system otherwise.  Which effect would apply?  Would all effects apply?  Using the percentage chance would that be the chance for both to apply or only one?  Which one?  I would recommend only one at a time and if the user applies a different effect then have it replace the existing one.

3. For this feature I would recommend and definitely request that you please create a separate permissions node for each effect.  While I may want someone to have the ability to use a command I may very well not want them to be able to apply that effect to their weapon and vice-versa.  This is very useful in the concept of "classes" which may have certain abilities but not others.

4. The percentage chance that after a player applies the effect to their weapon that the effect will actually be applied to their victim.  I would assume this would be calculated per strike of the weapon.  It is quite likely that this chance would need to be configured on a per effect basis.  For example,  if a sword has poison applied to it then I would more than likely choose 100% chance to apply.  I would not however be ok with 100% chance to apply blindness.  That would be a nightmare in PvP.

5. A 'cooldown' for the effect to be applied to a player's victim.  For example when a player applies the effect to their weapon and then begins attacking a group of 3 people and the effect transfers to the first victim, this option would control how long before the effect could be applied again to the same or any player.

6. The length of time that the effect would be applied to their weapon.  In other words the length of time that there would be a chance that their weapon could apply the effect to a victim.

7. What is defined as a weapon?  Perhaps a list of item id's could be specified here as to what constitutes a weapon.  For example if a player were going to be a healer for example a stick may qualify as their 'weapon' and they could have the heal effect applied to that stick.  However under normal circumstances it would be a bit dumb for it to be applied to a block of gravel.  However it is not unheard of for people to use books to apply 'magical' effects.  Considering that most servers apply at least one or two RP elements to their server this would be a nice feature to have control of.

8. This one is the lowest priority by far but is something someone would ask about eventually: Bow & Arrow?

NOTE:

      a. A much easier but far less customizable/flexible option to deal with #'s 4,5 and 6 would be to add a cooldown to the command which applies the effect to their weapon and but then make it so that the 'weapon effect' is no longer applied to the weapon after the first time it is transferred to a victim.

      b. An additional alternative would be to implement #4 and then to add a node which would specify the max number of times that the effect could be applied to the player's victims before the 'weapon effect' is no longer applied to the player's weapon.

Caveats:

1. Persistence?  When a player applies an effect to their weapon then relogs (logs off and back on) it would be fine if the weapon effect was no longer applied however the cooldown would in theory still need to be applied.  The cooldown however would NOT need to be persistent across server reboots of course.  Once the effect has been applied to the victim however that very much so does need to be persisent across relogs of the victim.